The present invention relates to a method for controlling a respirator for therapeutic treatment of sleep apnea as well as to a respirator for performing the inventive method, whereby the phase angle (time difference between respiratory flow and respiratory pressure) and the pressure amplitude correlated to the respiratory resistance are measured as well as the individual respiratory resistance (base value) of the pressure amplitude of a patient with the aid of oscilloresistometry and the respiratory gas pressure is controlled as a function of these values.
Such a device is, for example, known from U.S. Pat. No. 5,617,846.
A considerable number of people suffer from sleeping disorders which affect their daily well-being and their social and professional capabilities as well as their quality of life. Such sleeping disorders include obstructive sleep apnea in which, due to a reduction of the muscle tone, the upper respiratory path ways partly or entirely collapse. The condition primarily treated by the so-called CPAP therapy (CPAP=Continuous Positive Airway Pressure). This is achieved by supplying the patient during the sleeping hours with an air stream of a respiratory gas through a nasal mask. This mask is connected with a hose to the respirator that includes a fan which produces a gas stream with pressure that can be adjusted to be between 5 and 20 mbar above ambient pressure. The gas flow is supplied to the patient with constant pressure or, for facilitating breathing of the patient, is lowered during exhaling to a reduced pressure level. Even though sleep apnea phases occur only for very short periods of time and occupy only a minimal portion of the sleeping hours, the fan in this method operates continuously, i.e., during the entire sleeping hours (night). This reduces acceptance by the patient for such treatment. In order to eliminate these disadvantages, a method for controlling a respirator as well as a respiratory device for performing this method are know from European Patent Application 0 705 615. By oscilloresistometry (oscillatory resistance measurement=ORM) changes in the phase angle of the oscillating pressure amplitude, which is proportional to the respiratory resistance of the patient, are continuously measured whereby after determination of the individual respiratory resistance value (base value of the pressure amplitude) a respiratory gas is supplied under pressure to the patient when deviations from this value are detected. The gas supply is terminated as soon as the base value has been reached again or is at least approximately reached. The dynamics of such a method are determined by the time which elapses from the point of detecting the resistance increase (increase of the pressure amplitude) until the therapeutically effective CPAP pressure has been reached. Within this time window, i.e., even before reaching the therapeutically effective CPAP pressure, sleep apnea may occur.
It is therefore an object of the present invention to improve the sensitivity of the control method by shortening the response time.